[HUDI-1226] Fix ComplexKeyGenerator for non-partitioned tables

[satishkotha]

What is the purpose of the pull request

ComplexKeyGenerator getPartitionPath doesnt seem to work well with non-partitioned tables. Fix it and add test case

Brief change log

• Ignore empty string for partition path fields
• Return "" for partitionPath if there are no partition path fields defined

Verify this pull request

This change added tests

Committer checklist

• Has a corresponding JIRA in PR title & commit

• Commit message is descriptive of the change

• CI is green

• Necessary doc changes done or have another open PR

• For large changes, please consider breaking it into sub-tasks under an umbrella JIRA.

[n3nash]

@satishkotha was it throwing an exception before this change ?

[satishkotha]

@satishkotha was it throwing an exception before this change ?

From https://issues.apache.org/jira/browse/HUDI-1226,

1. If we pass empty string(-hoodie-conf hoodie.datasource.write.partitionpath.field=), generator returns 'default' as partitionpath
2. if we pass delimiter alone (-hoodie-conf hoodie.datasource.write.partitionpath.field=,), it throws
   java.lang.StringIndexOutOfBoundsException: String index out of range: -1

at java.lang.AbstractStringBuilder.deleteCharAt(AbstractStringBuilder.java:824)
at java.lang.StringBuilder.deleteCharAt(StringBuilder.java:253)
at org.apache.hudi.keygen.KeyGenUtils.getRecordPartitionPath(KeyGenUtils.java:80)
at org.apache.hudi.keygen.ComplexKeyGenerator.getPartitionPath(ComplexKeyGenerator.java:52)
at org.apache.hudi.keygen.BuiltinKeyGenerator.getKey(BuiltinKeyGenerator.java:75)

[satishkotha]

@satishkotha was it throwing an exception before this change ?

From https://issues.apache.org/jira/browse/HUDI-1226,

1. If we pass empty string(-hoodie-conf hoodie.datasource.write.partitionpath.field=), generator returns 'default' as partitionpath
2. if we pass delimiter alone (-hoodie-conf hoodie.datasource.write.partitionpath.field=,), it throws
   java.lang.StringIndexOutOfBoundsException: String index out of range: -1

at java.lang.AbstractStringBuilder.deleteCharAt(AbstractStringBuilder.java:824)
at java.lang.StringBuilder.deleteCharAt(StringBuilder.java:253)
at org.apache.hudi.keygen.KeyGenUtils.getRecordPartitionPath(KeyGenUtils.java:80)
at org.apache.hudi.keygen.ComplexKeyGenerator.getPartitionPath(ComplexKeyGenerator.java:52)
at org.apache.hudi.keygen.BuiltinKeyGenerator.getKey(BuiltinKeyGenerator.java:75)

@n3nash ^